Field of the Invention
The present invention relates to a device having a large electrically heatable honeycomb body, in which the honeycomb body has sheet-metal foils that form channels and are electrically contacted by a housing. The invention can be used in particular in the automotive field where, for example, electrically heatable honeycomb bodies with a diameter of greater than 200 mm are required. The invention also relates to a motor vehicle having at least one such device.
The development of electrically heatable metallic honeycomb bodies has been driven forward significantly by the corporate assignee of the instant application in the last 20 years. Reference may be made, for example, to International Publication No. WO 92/02714, corresponding to U.S. Pat. No. 5,411,711. That document describes a honeycomb body constructed from at least partially structured metal sheets which are disposed in layers and which form a plurality of channels that can be traversed by an exhaust gas and run from one end side to the other. Furthermore, a plurality of areal gaps and/or electrically insulating layers which run in a direction from one end side to the other are positioned in such a way that at least one continuous electrically conductive current path which runs in a cross-sectional plane is provided. The metal sheets are electrically conductively connected at their one end to a first terminal contact and at their other end to a second terminal contact. In that way, it is made possible, in particular, to realize a supply and discharge of current substantially in one plane.
A slightly different concept may also be gathered from International Publication No. WO 92/13636, corresponding to U.S. Pat. Nos. 5,525,309; 5,382,774 and 5,370,943. The electrically heatable honeycomb body described therein has at least two disks which are spaced apart from one another and which are positioned relative to one another through the use of support pins. That configuration makes it possible for a first disk to be constructed in such a way that it can be heated quickly by through-flowing exhaust gas or by electrical current, and/or for the mechanical strength of the honeycomb body to be ensured. In particular, that document also explains that it is possible for the metal sheets in the disks which are disposed in series to be connected to one another in an electrically conductive fashion through the use of support pins. It is proposed, in particular, that a meandering current path be formed which connects individual metal sheet packs of the two disks in series in a continuous fashion.
Even though the concepts explained above have substantially been very well proven and may presently be used in a wide variety of applications, there is nevertheless a demand for honeycomb bodies which are of even more simple construction and which are in particular suitable for generating uniform heating power even in the case of large cross sections or diameters (for example in static applications or in applications in the utility or commercial vehicle field).